Zend_Service_Amazon_Ec2: Reserved Instances

With Amazon EC2 Reserved Instances, you can make a low one-time payment
for each instance to reserve and receive a significant discount on the hourly
usage charge for that instance.

Amazon EC2 Reserved Instances are based on instance type and location
(region and Availability Zone) for a specified period of time (e.g.,
1 year or 3 years) and are only available for Linux or UNIX instances.

How Reserved Instances are Applied

Reserved Instances are applied to instances that meet the type/location
criteria during the specified period. In this example, a user is running
the following instances:

(4) m1.small instances in Availability Zone us-east-1a

(4) c1.medium instances in Availability Zone us-east-1b

(2) c1.xlarge instances in Availability Zone us-east-1b

The user then purchases the following Reserved Instances.

(2) m1.small instances in Availability Zone us-east-1a

(2) c1.medium instances in Availability Zone us-east-1a

(2) m1.xlarge instances in Availability Zone us-east-1a

Amazon EC2 applies the two m1.small Reserved Instances to two of the
instances in Availability Zone us-east-1a. Amazon EC2 doesn't apply
the two c1.medium Reserved Instances because the c1.medium instances are in a different
Availability Zone and does not apply the m1.xlarge Reserved Instances because there are
no running m1.xlarge instances.

Reserved Instances Usage

Example #1 Describes Reserved Instances that you purchased

describeInstances() will return information about a
reserved instance or instances that you purchased.

describeOfferings() Describes Reserved Instance offerings
that are available for purchase. With Amazon EC2 Reserved
Instances, you purchase the right to launch Amazon EC2 instances
for a period of time (without getting insufficient capacity errors) and pay a lower
usage rate for the actual time used.

purchaseOffering() Purchases a Reserved Instance for use
with your account. With Amazon EC2 Reserved Instances, you
purchase the right to launch Amazon EC2 instances for a period
of time (without getting insufficient capacity errors) and pay a lower usage rate
for the actual time used.